DIY Subwoofer plans

Discussion in 'Home Cinema Building DIY' started by jpwhaley, Jul 18, 2002.

  1. jpwhaley

    jpwhaley
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    Although tempted by Uncle Eric Q100 and the Power Buys I have decided that building my own subwoofer will be more fun and hopefully sound a lot better.

    Being my first speaker build I wanted to get as much advice as possible espically from those of you who have already built their own.

    The facts:
    My budget is 300GBP and my room is 15ft x 10ft. The sub is to be used for both music & movies and having a semi detached house extreme loudness is not desired just a tight deep bass. I also have a bit of space so I don't need to compromise on sound quality to have a small box although I will need to disguise a very big box as a bit of funiture. I plan to start the build late september giving me a couple of months to get parts and draw up plans.

    I was thinking of building something like a 80litre sealed box, shiva driver and bkelec 300W plate, based on Adire Audio White Paper. I would prefer to source the driver from the UK so can anyone recommend a 12" shiva equivalent that I can get in the UK? Also any comments on subwoofer design and your own experiences will be welcome.

    Hopefully we can start up a good discussion that will help myself and others thinking of building their own subwoofer.

    thanks,

    Jeremy
     
  2. ReTrO

    ReTrO
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    You can get the Adire Audio Shiva II from GaryG on these forums.

    You can email him at: [email protected]
     
  3. jpwhaley

    jpwhaley
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    Thanks ReTro, I tried GaryG but he has stopped his dealership so the only way to get the Shiva is to import it. This is why I was wondering if there was another suitable driver that I could use instead.
     
  4. ReTrO

    ReTrO
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    Don't really know what to recommend. Ramius should be helpfull.

    I am building a compact sub using a JL 10W3 D4, mainly because it is pretty good, and I can get it through work.
     
  5. GaryG

    GaryG
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  6. jpwhaley

    jpwhaley
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    The specs of the ACI SV12 do look very good but it has a high Vas of 250 compared to a Shiva at 151 or Peerless at 137. Won't this make the driver more suitable for a vented box than a sealed one?
     
  7. banners

    banners
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    hi all, actually using a aci sv12 driver for my diy sub(well when complete!). using the software from the site mentioned earlier, sealed 130l box= f3~31Hz f10~19Hz. same size box vented= f3~22Hz f10~17.5Hz. both very impressive from where i'm looking from, I may even try to incorporate both in the same box to evaluate more easily.
    get the software and play!
    cheers steve
     
  8. GaryG

    GaryG
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    From The Loudspeaker Design Cookbook by Vance Dickason:


    "Woofers intended for use in closed-box systems are characterised by low free-air resonance (fs), relatively high cone mass, and long voice coils.... In terms of driver Qts, closed-box loudspeakers generally require woofers with a fairly high Qts of greater than 0.3... R.Small suggested a good rule-of-thumb which he called Efficiency Bandwidth Product (EBP).

    EBP is quantified by:


    EBP = Resonance Frequency / Driver Electrical Q

    or EBP = fs / Qes

    EBP in the vicinity of 50 or less indicates a sealed enclosure would be more suitable, while EBPs of about 100 suggest a vented enclosure."



    For the SV12 the EBP is approximately 43.

    ACI manufacture the Titan sealed sub which is a design that has been copied many time by DIYers. Here's some additional info on the Titan:

    www.soundstage.com/entry11.htm
    www.audioc.com/speakers/Reviews/titanr.htm
    www.subwoofers.com/HomeAud/Kits/titan/titan_review.htm

    The plans are available here:

    www.subwoofers.com/HomeAud/kits/titan/titan.asp
     
  9. jpwhaley

    jpwhaley
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    Thanks for the feedback,

    At the moment I do not have access to a windows PC (I am in France working till mid August) so I can't use the modeling software. I have been basing my calculation using the spreadsheet from diysubwoofers.org for sealed enclosures. In my understanding (which is limited) VAS is directly proportional to enclosure volume. So if everything else remains constant for a given value of Q, a larger VAS requires a larger cabinet size. That is why I thought the ACI might be better for a vented enclosure.

    Using the Efficiency Bandwidth Product (EBP) rule the ACI (EBP = 43) driver appears better than the Shiva (EBP = 51) and certainly the Peerless driver (EBP = 86) that I was also looking at. A cheap copy of the loudspeaker cookbook will be handy.

    Using my spreadsheet a sealed design for a Q of 0.707 will require a 125 litre enclosure. Which seems to similar to what banners is designing.

    Does anyone also have a rule of thumb on the effect of using filling. ie For the same Q using fillying can I reduce the box volume by x %? Also for the filling can just use pillow stuffing?

    Final question, I see lots of designs use egg shelled foam to line the insides of the enclosure to reuce standing waves. Does this help and do you take the volume of the foam into account for enclosure size?
     
  10. smallangryboy

    smallangryboy
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    From what I can gather from Adire's own designs for Sealed Shiva subwoofer designs here an enclosure of 54 litres is recommended to achieve a Q of 0.707 if you were to go with the Shiva driver.
     
  11. HTnewb

    HTnewb
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    Hello,

    I cannot seem to find this software you mention, could you post the link again please? :lease:

    TIA!
    HTnewb
     
  12. banners

    banners
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    Hello HTnewb if you look at the dates the original posts are nearly 2 1/2 years old!! Hence I don't think the software is there any more. There should be a wealth of info on the net tho'.
    Do a little searching on google. Winisd is a helpful little program to help design boxes.
    HTH
    Steve
     
  13. jpwhaley

    jpwhaley
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  14. Londondecca

    Londondecca
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    It might also be worth looking at www.diyaudio.com under loudspeakers/subwoofers
     

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